pub fn hello_mod1() {
    println!("Hello world Mod1!");
    println!("now have some value: ");

    let number: i32 = 1;
    println!("number : i32 =  1  ,{} ", number);

    {
        let number: i32 = 2;
        println!("number : i32 =  2  , {}", number);
    }

    println!("number : i32 =  unkown  ,{} ", number);

    let mut number: i32 = 3;
    println!("number : i32 =  3  ,{} ", number);

    number = 4;
    println!("number : i32 = ->4  ,{} ", number);
}
